The answer to this question largely depends on what the topic of this paragraph is going to be. Generally speaking, each middle paragraph that you write should be built around one point related to your thesis statement, and this point should be clearly indicated in the opening of your paragraph. This is often called or refered to as a "topic sentence." Therefore, let us just pretend you are writing an essay on the various themes in The Adventures of Huckleberry Finn. Each of your middle paragraphs will relate to the presentation and discussion of a different theme. Your opening sentence of your body paragraph should clearly indicate to the reader what theme you will be addressing in that paragraph. Therefore, a good opening sentence might be:
The theme of hypocrisy in Christianity is clearly evident from the way in which Christianity is depicted in this novel.
This of course is a short and simple sentence that makes it absolutely clear to the reader that this paragraph is going to be based on the theme of hypocrisy in Christianity. You will then in the rest of the paragraph continue to develop this theme, discussing its presentation and including quotes with pertinent analysis. Signposting is the key in writing essays, and a clear and simple topic sentence to open a body paragraph is vital.